In some medical applications, for example in the field of dental anaesthesia, it is necessary to pass through dense tissue, e.g., the cortical bone of a jawbone to inject a pharmaceutical product at the proper site. To arrive thereat, first a drill is used for perforation followed by injection using a needle. According to an alternative method, a perforator needle is used to perforate and also to inject.
If a needle is used for perforation, the simplest means, which requires least space, is to use the container of the anaesthetic product as transmission shaft between the driving means and the needle. An adaptor part must therefore be designed capable of transmitting the torque of the pharmaceutical product container to the perforator needle. The adapter part must be perfectly coaxial with the container to withstand the high rotation speeds without generating vibrations or too much noise. In addition, the adapter part must be capable of being sterilized at high temperatures (between 130 and 140° C.) since the perforator needle, and frequently also the end of the adapter part receiving the needle, are in contact with the patient, and notably in the patient's mouth.
The adapter parts used prior to the invention are formed in plastic materials which use the deformation of the material to grip the container and thereby transmit torque to the perforator needle. However, the materials used have proved to be disadvantageous insofar as they show early wearing due to high internal stresses when adapting to the different diameters of the containers. These high internal stresses prevent fitting over long distances, which is adverse to the coaxiality of rotation of the container relative to the needle.
Other plastic holders have a length close to the length of the containers and, to adapt to the different container diameters, they have rubber rings hence inner ring seals housed in annular grooves provided for this purpose in the holders.
However, these holders have proved to have shortcomings on account of the poor resistance of the rubber products over time to sterilisation when they are confronted with temperatures of between 130° C. and 140° C. and to cleaning products. Additionally, the rubber seals cause an increase in the outer diameter of the holder. This increase leads to an increase in the diameter of the hand-piece which gives rise to a major problem insofar as it is always sought to obtain maximum ease of handling, optimal vision and small volume.
Regarding glass containers, through their manufacturing mode these show major variations in diameter and length. Some models are also provided with an anti-breakage plastic film which further increases variations in diameter and modifies the contact surface imparting poor sliding properties for the rubber seals.